20 files changed, 140 insertions, 240 deletions

diff --git a/arch/ia64/include/asm/ptrace.h b/arch/ia64/include/asm/ptrace.h
index a10a498eede1..402874489890 100644
--- a/arch/ia64/include/asm/ptrace.h
+++ b/arch/ia64/include/asm/ptrace.h
@@ -139,10 +139,6 @@ static inline long regs_return_value(struct pt_regs *regs)
   #define arch_ptrace_stop_needed() \
 	(!test_thread_flag(TIF_RESTORE_RSE))
 
-  extern void ptrace_attach_sync_user_rbs (struct task_struct *);
-  #define arch_ptrace_attach(child) \
-	ptrace_attach_sync_user_rbs(child)
-
   #define arch_has_single_step()  (1)
   #define arch_has_block_step()   (1)
 
diff --git a/arch/ia64/kernel/ptrace.c b/arch/ia64/kernel/ptrace.c
index 4fc6e38a8459..ab8aeb34d1d9 100644
--- a/arch/ia64/kernel/ptrace.c
+++ b/arch/ia64/kernel/ptrace.c
@@ -618,63 +618,6 @@ void ia64_sync_krbs(void)
 }
 
 /*
- * After PTRACE_ATTACH, a thread's register backing store area in user
- * space is assumed to contain correct data whenever the thread is
- * stopped.  arch_ptrace_stop takes care of this on tracing stops.
- * But if the child was already stopped for job control when we attach
- * to it, then it might not ever get into ptrace_stop by the time we
- * want to examine the user memory containing the RBS.
- */
-void
-ptrace_attach_sync_user_rbs (struct task_struct *child)
-{
-	int stopped = 0;
-	struct unw_frame_info info;
-
-	/*
-	 * If the child is in TASK_STOPPED, we need to change that to
-	 * TASK_TRACED momentarily while we operate on it.  This ensures
-	 * that the child won't be woken up and return to user mode while
-	 * we are doing the sync.  (It can only be woken up for SIGKILL.)
-	 */
-
-	read_lock(&tasklist_lock);
-	if (child->sighand) {
-		spin_lock_irq(&child->sighand->siglock);
-		if (READ_ONCE(child->__state) == TASK_STOPPED &&
-		    !test_and_set_tsk_thread_flag(child, TIF_RESTORE_RSE)) {
-			set_notify_resume(child);
-
-			WRITE_ONCE(child->__state, TASK_TRACED);
-			stopped = 1;
-		}
-		spin_unlock_irq(&child->sighand->siglock);
-	}
-	read_unlock(&tasklist_lock);
-
-	if (!stopped)
-		return;
-
-	unw_init_from_blocked_task(&info, child);
-	do_sync_rbs(&info, ia64_sync_user_rbs);
-
-	/*
-	 * Now move the child back into TASK_STOPPED if it should be in a
-	 * job control stop, so that SIGCONT can be used to wake it up.
-	 */
-	read_lock(&tasklist_lock);
-	if (child->sighand) {
-		spin_lock_irq(&child->sighand->siglock);
-		if (READ_ONCE(child->__state) == TASK_TRACED &&
-		    (child->signal->flags & SIGNAL_STOP_STOPPED)) {
-			WRITE_ONCE(child->__state, TASK_STOPPED);
-		}
-		spin_unlock_irq(&child->sighand->siglock);
-	}
-	read_unlock(&tasklist_lock);
-}
-
-/*
  * Write f32-f127 back to task->thread.fph if it has been modified.
  */
 inline void
diff --git a/arch/um/include/asm/thread_info.h b/arch/um/include/asm/thread_info.h
index 1395cbd7e340..c7b4b49826a2 100644
--- a/arch/um/include/asm/thread_info.h
+++ b/arch/um/include/asm/thread_info.h
@@ -60,6 +60,7 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_RESTORE_SIGMASK	7
 #define TIF_NOTIFY_RESUME	8
 #define TIF_SECCOMP		9	/* secure computing */
+#define TIF_SINGLESTEP		10	/* single stepping userspace */
 
 #define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)
 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
@@ -68,5 +69,6 @@ static inline struct thread_info *current_thread_info(void)
 #define _TIF_MEMDIE		(1 << TIF_MEMDIE)
 #define _TIF_SYSCALL_AUDIT	(1 << TIF_SYSCALL_AUDIT)
 #define _TIF_SECCOMP		(1 << TIF_SECCOMP)
+#define _TIF_SINGLESTEP		(1 << TIF_SINGLESTEP)
 
 #endif
diff --git a/arch/um/kernel/exec.c b/arch/um/kernel/exec.c
index c85e40c72779..58938d75871a 100644
--- a/arch/um/kernel/exec.c
+++ b/arch/um/kernel/exec.c
@@ -43,7 +43,7 @@ void start_thread(struct pt_regs *regs, unsigned long eip, unsigned long esp)
 {
 	PT_REGS_IP(regs) = eip;
 	PT_REGS_SP(regs) = esp;
-	current->ptrace &= ~PT_DTRACE;
+	clear_thread_flag(TIF_SINGLESTEP);
 #ifdef SUBARCH_EXECVE1
 	SUBARCH_EXECVE1(regs->regs);
 #endif
diff --git a/arch/um/kernel/process.c b/arch/um/kernel/process.c
index 181cc9aafb25..80b90b1276a1 100644
--- a/arch/um/kernel/process.c
+++ b/arch/um/kernel/process.c
@@ -336,7 +336,7 @@ int singlestepping(void * t)
 {
 	struct task_struct *task = t ? t : current;
 
-	if (!(task->ptrace & PT_DTRACE))
+	if (!test_thread_flag(TIF_SINGLESTEP))
 		return 0;
 
 	if (task->thread.singlestep_syscall)
diff --git a/arch/um/kernel/ptrace.c b/arch/um/kernel/ptrace.c
index bfaf6ab1ac03..5154b27de580 100644
--- a/arch/um/kernel/ptrace.c
+++ b/arch/um/kernel/ptrace.c
@@ -11,7 +11,7 @@
 
 void user_enable_single_step(struct task_struct *child)
 {
-	child->ptrace |= PT_DTRACE;
+	set_tsk_thread_flag(child, TIF_SINGLESTEP);
 	child->thread.singlestep_syscall = 0;
 
 #ifdef SUBARCH_SET_SINGLESTEPPING
@@ -21,7 +21,7 @@ void user_enable_single_step(struct task_struct *child)
 
 void user_disable_single_step(struct task_struct *child)
 {
-	child->ptrace &= ~PT_DTRACE;
+	clear_tsk_thread_flag(child, TIF_SINGLESTEP);
 	child->thread.singlestep_syscall = 0;
 
 #ifdef SUBARCH_SET_SINGLESTEPPING
@@ -120,7 +120,7 @@ static void send_sigtrap(struct uml_pt_regs *regs, int error_code)
 }
 
 /*
- * XXX Check PT_DTRACE vs TIF_SINGLESTEP for singlestepping check and
+ * XXX Check TIF_SINGLESTEP for singlestepping check and
  * PT_PTRACED vs TIF_SYSCALL_TRACE for syscall tracing check
  */
 int syscall_trace_enter(struct pt_regs *regs)
@@ -144,7 +144,7 @@ void syscall_trace_leave(struct pt_regs *regs)
 	audit_syscall_exit(regs);
 
 	/* Fake a debug trap */
-	if (ptraced & PT_DTRACE)
+	if (test_thread_flag(TIF_SINGLESTEP))
 		send_sigtrap(&regs->regs, 0);
 
 	if (!test_thread_flag(TIF_SYSCALL_TRACE))
diff --git a/arch/um/kernel/signal.c b/arch/um/kernel/signal.c
index 88cd9b5c1b74..ae4658f576ab 100644
--- a/arch/um/kernel/signal.c
+++ b/arch/um/kernel/signal.c
@@ -53,7 +53,7 @@ static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 	unsigned long sp;
 	int err;
 
-	if ((current->ptrace & PT_DTRACE) && (current->ptrace & PT_PTRACED))
+	if (test_thread_flag(TIF_SINGLESTEP) && (current->ptrace & PT_PTRACED))
 		singlestep = 1;
 
 	/* Did we come from a system call? */
@@ -128,7 +128,7 @@ void do_signal(struct pt_regs *regs)
 	 * on the host.  The tracing thread will check this flag and
 	 * PTRACE_SYSCALL if necessary.
 	 */
-	if (current->ptrace & PT_DTRACE)
+	if (test_thread_flag(TIF_SINGLESTEP))
 		current->thread.singlestep_syscall =
 			is_syscall(PT_REGS_IP(&current->thread.regs));
 
diff --git a/arch/x86/kernel/step.c b/arch/x86/kernel/step.c
index 0f3c307b37b3..8e2b2552b5ee 100644
--- a/arch/x86/kernel/step.c
+++ b/arch/x86/kernel/step.c
@@ -180,8 +180,7 @@ void set_task_blockstep(struct task_struct *task, bool on)
 	 *
 	 * NOTE: this means that set/clear TIF_BLOCKSTEP is only safe if
 	 * task is current or it can't be running, otherwise we can race
-	 * with __switch_to_xtra(). We rely on ptrace_freeze_traced() but
-	 * PTRACE_KILL is not safe.
+	 * with __switch_to_xtra(). We rely on ptrace_freeze_traced().
 	 */
 	local_irq_disable();
 	debugctl = get_debugctlmsr();
diff --git a/arch/xtensa/kernel/ptrace.c b/arch/xtensa/kernel/ptrace.c
index 22cdaa6729d3..f29477162ede 100644
--- a/arch/xtensa/kernel/ptrace.c
+++ b/arch/xtensa/kernel/ptrace.c
@@ -224,12 +224,12 @@ const struct user_regset_view *task_user_regset_view(struct task_struct *task)
 
 void user_enable_single_step(struct task_struct *child)
 {
-	child->ptrace |= PT_SINGLESTEP;
+	set_tsk_thread_flag(child, TIF_SINGLESTEP);
 }
 
 void user_disable_single_step(struct task_struct *child)
 {
-	child->ptrace &= ~PT_SINGLESTEP;
+	clear_tsk_thread_flag(child, TIF_SINGLESTEP);
 }
 
 /*
diff --git a/arch/xtensa/kernel/signal.c b/arch/xtensa/kernel/signal.c
index c9ffd42db873..876d5df157ed 100644
--- a/arch/xtensa/kernel/signal.c
+++ b/arch/xtensa/kernel/signal.c
@@ -472,7 +472,7 @@ static void do_signal(struct pt_regs *regs)
 		/* Set up the stack frame */
 		ret = setup_frame(&ksig, sigmask_to_save(), regs);
 		signal_setup_done(ret, &ksig, 0);
-		if (current->ptrace & PT_SINGLESTEP)
+		if (test_thread_flag(TIF_SINGLESTEP))
 			task_pt_regs(current)->icountlevel = 1;
 
 		return;
@@ -498,7 +498,7 @@ static void do_signal(struct pt_regs *regs)
 	/* If there's no signal to deliver, we just restore the saved mask.  */
 	restore_saved_sigmask();
 
-	if (current->ptrace & PT_SINGLESTEP)
+	if (test_thread_flag(TIF_SINGLESTEP))
 		task_pt_regs(current)->icountlevel = 1;
 	return;
 }
diff --git a/drivers/tty/tty_jobctrl.c b/drivers/tty/tty_jobctrl.c
index 80b86a7992b5..0d04287da098 100644
--- a/drivers/tty/tty_jobctrl.c
+++ b/drivers/tty/tty_jobctrl.c
@@ -215,8 +215,8 @@ int tty_signal_session_leader(struct tty_struct *tty, int exit_session)
 				spin_unlock_irq(&p->sighand->siglock);
 				continue;
 			}
-			__group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p);
-			__group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p);
+			send_signal_locked(SIGHUP, SEND_SIG_PRIV, p, PIDTYPE_TGID);
+			send_signal_locked(SIGCONT, SEND_SIG_PRIV, p, PIDTYPE_TGID);
 			put_pid(p->signal->tty_old_pgrp);  /* A noop */
 			spin_lock(&tty->ctrl.lock);
 			tty_pgrp = get_pid(tty->ctrl.pgrp);
diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h
index db4509587d2c..c952c5ba8fab 100644
--- a/include/linux/ptrace.h
+++ b/include/linux/ptrace.h
@@ -30,7 +30,6 @@ extern int ptrace_access_vm(struct task_struct *tsk, unsigned long addr,
 
 #define PT_SEIZED	0x00010000	/* SEIZE used, enable new behavior */
 #define PT_PTRACED	0x00000001
-#define PT_DTRACE	0x00000002	/* delayed trace (used on um) */
 
 #define PT_OPT_FLAG_SHIFT	3
 /* PT_TRACE_* event enable flags */
@@ -47,12 +46,6 @@ extern int ptrace_access_vm(struct task_struct *tsk, unsigned long addr,
 #define PT_EXITKILL		(PTRACE_O_EXITKILL << PT_OPT_FLAG_SHIFT)
 #define PT_SUSPEND_SECCOMP	(PTRACE_O_SUSPEND_SECCOMP << PT_OPT_FLAG_SHIFT)
 
-/* single stepping state bits (used on ARM and PA-RISC) */
-#define PT_SINGLESTEP_BIT	31
-#define PT_SINGLESTEP		(1<<PT_SINGLESTEP_BIT)
-#define PT_BLOCKSTEP_BIT	30
-#define PT_BLOCKSTEP		(1<<PT_BLOCKSTEP_BIT)
-
 extern long arch_ptrace(struct task_struct *child, long request,
 			unsigned long addr, unsigned long data);
 extern int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len);
diff --git a/include/linux/sched.h b/include/linux/sched.h
index b89c8571187b..c46f3a63b758 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -103,7 +103,7 @@ struct task_group;
 /* Convenience macros for the sake of set_current_state: */
 #define TASK_KILLABLE			(TASK_WAKEKILL | TASK_UNINTERRUPTIBLE)
 #define TASK_STOPPED			(TASK_WAKEKILL | __TASK_STOPPED)
-#define TASK_TRACED			(TASK_WAKEKILL | __TASK_TRACED)
+#define TASK_TRACED			__TASK_TRACED
 
 #define TASK_IDLE			(TASK_UNINTERRUPTIBLE | TASK_NOLOAD)
 
@@ -118,11 +118,9 @@ struct task_group;
 
 #define task_is_running(task)		(READ_ONCE((task)->__state) == TASK_RUNNING)
 
-#define task_is_traced(task)		((READ_ONCE(task->__state) & __TASK_TRACED) != 0)
-
-#define task_is_stopped(task)		((READ_ONCE(task->__state) & __TASK_STOPPED) != 0)
-
-#define task_is_stopped_or_traced(task)	((READ_ONCE(task->__state) & (__TASK_STOPPED | __TASK_TRACED)) != 0)
+#define task_is_traced(task)		((READ_ONCE(task->jobctl) & JOBCTL_TRACED) != 0)
+#define task_is_stopped(task)		((READ_ONCE(task->jobctl) & JOBCTL_STOPPED) != 0)
+#define task_is_stopped_or_traced(task)	((READ_ONCE(task->jobctl) & (JOBCTL_STOPPED | JOBCTL_TRACED)) != 0)
 
 /*
  * Special states are those that do not use the normal wait-loop pattern. See
diff --git a/include/linux/sched/jobctl.h b/include/linux/sched/jobctl.h
index fa067de9f1a9..68876d0a7ef9 100644
--- a/include/linux/sched/jobctl.h
+++ b/include/linux/sched/jobctl.h
@@ -19,6 +19,10 @@ struct task_struct;
 #define JOBCTL_TRAPPING_BIT	21	/* switching to TRACED */
 #define JOBCTL_LISTENING_BIT	22	/* ptracer is listening for events */
 #define JOBCTL_TRAP_FREEZE_BIT	23	/* trap for cgroup freezer */
+#define JOBCTL_PTRACE_FROZEN_BIT	24	/* frozen for ptrace */
+
+#define JOBCTL_STOPPED_BIT	26	/* do_signal_stop() */
+#define JOBCTL_TRACED_BIT	27	/* ptrace_stop() */
 
 #define JOBCTL_STOP_DEQUEUED	(1UL << JOBCTL_STOP_DEQUEUED_BIT)
 #define JOBCTL_STOP_PENDING	(1UL << JOBCTL_STOP_PENDING_BIT)
@@ -28,6 +32,10 @@ struct task_struct;
 #define JOBCTL_TRAPPING		(1UL << JOBCTL_TRAPPING_BIT)
 #define JOBCTL_LISTENING	(1UL << JOBCTL_LISTENING_BIT)
 #define JOBCTL_TRAP_FREEZE	(1UL << JOBCTL_TRAP_FREEZE_BIT)
+#define JOBCTL_PTRACE_FROZEN	(1UL << JOBCTL_PTRACE_FROZEN_BIT)
+
+#define JOBCTL_STOPPED		(1UL << JOBCTL_STOPPED_BIT)
+#define JOBCTL_TRACED		(1UL << JOBCTL_TRACED_BIT)
 
 #define JOBCTL_TRAP_MASK	(JOBCTL_TRAP_STOP | JOBCTL_TRAP_NOTIFY)
 #define JOBCTL_PENDING_MASK	(JOBCTL_STOP_PENDING | JOBCTL_TRAP_MASK)
diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index 20ed5ba2bde4..cafbe03eed01 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -294,8 +294,10 @@ static inline int kernel_dequeue_signal(void)
 static inline void kernel_signal_stop(void)
 {
 	spin_lock_irq(&current->sighand->siglock);
-	if (current->jobctl & JOBCTL_STOP_DEQUEUED)
+	if (current->jobctl & JOBCTL_STOP_DEQUEUED) {
+		current->jobctl |= JOBCTL_STOPPED;
 		set_special_state(TASK_STOPPED);
+	}
 	spin_unlock_irq(&current->sighand->siglock);
 
 	schedule();
@@ -444,13 +446,23 @@ extern void calculate_sigpending(void);
 
 extern void signal_wake_up_state(struct task_struct *t, unsigned int state);
 
-static inline void signal_wake_up(struct task_struct *t, bool resume)
+static inline void signal_wake_up(struct task_struct *t, bool fatal)
 {
-	signal_wake_up_state(t, resume ? TASK_WAKEKILL : 0);
+	unsigned int state = 0;
+	if (fatal && !(t->jobctl & JOBCTL_PTRACE_FROZEN)) {
+		t->jobctl &= ~(JOBCTL_STOPPED | JOBCTL_TRACED);
+		state = TASK_WAKEKILL | __TASK_TRACED;
+	}
+	signal_wake_up_state(t, state);
 }
 static inline void ptrace_signal_wake_up(struct task_struct *t, bool resume)
 {
-	signal_wake_up_state(t, resume ? __TASK_TRACED : 0);
+	unsigned int state = 0;
+	if (resume) {
+		t->jobctl &= ~JOBCTL_TRACED;
+		state = __TASK_TRACED;
+	}
+	signal_wake_up_state(t, state);
 }
 
 void task_join_group_stop(struct task_struct *task);
diff --git a/include/linux/signal.h b/include/linux/signal.h
index a6db6f2ae113..3b98e7a28538 100644
--- a/include/linux/signal.h
+++ b/include/linux/signal.h
@@ -282,7 +282,8 @@ extern int do_send_sig_info(int sig, struct kernel_siginfo *info,
 				struct task_struct *p, enum pid_type type);
 extern int group_send_sig_info(int sig, struct kernel_siginfo *info,
 			       struct task_struct *p, enum pid_type type);
-extern int __group_send_sig_info(int, struct kernel_siginfo *, struct task_struct *);
+extern int send_signal_locked(int sig, struct kernel_siginfo *info,
+			      struct task_struct *p, enum pid_type type);
 extern int sigprocmask(int, sigset_t *, sigset_t *);
 extern void set_current_blocked(sigset_t *);
 extern void __set_current_blocked(const sigset_t *);
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 49c29baf9907..156a99283b11 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -185,7 +185,12 @@ static bool looks_like_a_spurious_pid(struct task_struct *task)
 	return true;
 }
 
-/* Ensure that nothing can wake it up, even SIGKILL */
+/*
+ * Ensure that nothing can wake it up, even SIGKILL
+ *
+ * A task is switched to this state while a ptrace operation is in progress;
+ * such that the ptrace operation is uninterruptible.
+ */
 static bool ptrace_freeze_traced(struct task_struct *task)
 {
 	bool ret = false;
@@ -197,7 +202,7 @@ static bool ptrace_freeze_traced(struct task_struct *task)
 	spin_lock_irq(&task->sighand->siglock);
 	if (task_is_traced(task) && !looks_like_a_spurious_pid(task) &&
 	    !__fatal_signal_pending(task)) {
-		WRITE_ONCE(task->__state, __TASK_TRACED);
+		task->jobctl |= JOBCTL_PTRACE_FROZEN;
 		ret = true;
 	}
 	spin_unlock_irq(&task->sighand->siglock);
@@ -207,23 +212,21 @@ static bool ptrace_freeze_traced(struct task_struct *task)
 
 static void ptrace_unfreeze_traced(struct task_struct *task)
 {
-	if (READ_ONCE(task->__state) != __TASK_TRACED)
-		return;
-
-	WARN_ON(!task->ptrace || task->parent != current);
+	unsigned long flags;
 
 	/*
-	 * PTRACE_LISTEN can allow ptrace_trap_notify to wake us up remotely.
-	 * Recheck state under the lock to close this race.
+	 * The child may be awake and may have cleared
+	 * JOBCTL_PTRACE_FROZEN (see ptrace_resume).  The child will
+	 * not set JOBCTL_PTRACE_FROZEN or enter __TASK_TRACED anew.
 	 */
-	spin_lock_irq(&task->sighand->siglock);
-	if (READ_ONCE(task->__state) == __TASK_TRACED) {
-		if (__fatal_signal_pending(task))
+	if (lock_task_sighand(task, &flags)) {
+		task->jobctl &= ~JOBCTL_PTRACE_FROZEN;
+		if (__fatal_signal_pending(task)) {
+			task->jobctl &= ~TASK_TRACED;
 			wake_up_state(task, __TASK_TRACED);
-		else
-			WRITE_ONCE(task->__state, TASK_TRACED);
+		}
+		unlock_task_sighand(task, &flags);
 	}
-	spin_unlock_irq(&task->sighand->siglock);
 }
 
 /**
@@ -256,7 +259,6 @@ static int ptrace_check_attach(struct task_struct *child, bool ignore_state)
 	 */
 	read_lock(&tasklist_lock);
 	if (child->ptrace && child->parent == current) {
-		WARN_ON(READ_ONCE(child->__state) == __TASK_TRACED);
 		/*
 		 * child->sighand can't be NULL, release_task()
 		 * does ptrace_unlink() before __exit_signal().
@@ -266,17 +268,9 @@ static int ptrace_check_attach(struct task_struct *child, bool ignore_state)
 	}
 	read_unlock(&tasklist_lock);
 
-	if (!ret && !ignore_state) {
-		if (!wait_task_inactive(child, __TASK_TRACED)) {
-			/*
-			 * This can only happen if may_ptrace_stop() fails and
-			 * ptrace_stop() changes ->state back to TASK_RUNNING,
-			 * so we should not worry about leaking __TASK_TRACED.
-			 */
-			WARN_ON(READ_ONCE(child->__state) == __TASK_TRACED);
-			ret = -ESRCH;
-		}
-	}
+	if (!ret && !ignore_state &&
+	    WARN_ON_ONCE(!wait_task_inactive(child, __TASK_TRACED)))
+		ret = -ESRCH;
 
 	return ret;
 }
@@ -475,8 +469,10 @@ static int ptrace_attach(struct task_struct *task, long request,
 	 * in and out of STOPPED are protected by siglock.
 	 */
 	if (task_is_stopped(task) &&
-	    task_set_jobctl_pending(task, JOBCTL_TRAP_STOP | JOBCTL_TRAPPING))
+	    task_set_jobctl_pending(task, JOBCTL_TRAP_STOP | JOBCTL_TRAPPING)) {
+		task->jobctl &= ~JOBCTL_STOPPED;
 		signal_wake_up_state(task, __TASK_STOPPED);
+	}
 
 	spin_unlock(&task->sighand->siglock);
 
@@ -846,8 +842,6 @@ static long ptrace_get_rseq_configuration(struct task_struct *task,
 static int ptrace_resume(struct task_struct *child, long request,
 			 unsigned long data)
 {
-	bool need_siglock;
-
 	if (!valid_signal(data))
 		return -EIO;
 
@@ -883,18 +877,12 @@ static int ptrace_resume(struct task_struct *child, long request,
 	 * Note that we need siglock even if ->exit_code == data and/or this
 	 * status was not reported yet, the new status must not be cleared by
 	 * wait_task_stopped() after resume.
-	 *
-	 * If data == 0 we do not care if wait_task_stopped() reports the old
-	 * status and clears the code too; this can't race with the tracee, it
-	 * takes siglock after resume.
 	 */
-	need_siglock = data && !thread_group_empty(current);
-	if (need_siglock)
-		spin_lock_irq(&child->sighand->siglock);
+	spin_lock_irq(&child->sighand->siglock);
 	child->exit_code = data;
+	child->jobctl &= ~JOBCTL_TRACED;
 	wake_up_state(child, __TASK_TRACED);
-	if (need_siglock)
-		spin_unlock_irq(&child->sighand->siglock);
+	spin_unlock_irq(&child->sighand->siglock);
 
 	return 0;
 }
@@ -1230,9 +1218,8 @@ int ptrace_request(struct task_struct *child, long request,
 		return ptrace_resume(child, request, data);
 
 	case PTRACE_KILL:
-		if (child->exit_state)	/* already dead */
-			return 0;
-		return ptrace_resume(child, request, SIGKILL);
+		send_sig_info(SIGKILL, SEND_SIG_NOINFO, child);
+		return 0;
 
 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
 	case PTRACE_GETREGSET:
@@ -1279,10 +1266,6 @@ int ptrace_request(struct task_struct *child, long request,
 	return ret;
 }
 
-#ifndef arch_ptrace_attach
-#define arch_ptrace_attach(child)	do { } while (0)
-#endif
-
 SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
 		unsigned long, data)
 {
@@ -1291,8 +1274,6 @@ SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
 
 	if (request == PTRACE_TRACEME) {
 		ret = ptrace_traceme();
-		if (!ret)
-			arch_ptrace_attach(current);
 		goto out;
 	}
 
@@ -1304,12 +1285,6 @@ SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
 
 	if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
 		ret = ptrace_attach(child, request, addr, data);
-		/*
-		 * Some architectures need to do book-keeping after
-		 * a ptrace attach.
-		 */
-		if (!ret)
-			arch_ptrace_attach(child);
 		goto out_put_task_struct;
 	}
 
@@ -1449,12 +1424,6 @@ COMPAT_SYSCALL_DEFINE4(ptrace, compat_long_t, request, compat_long_t, pid,
 
 	if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
 		ret = ptrace_attach(child, request, addr, data);
-		/*
-		 * Some architectures need to do book-keeping after
-		 * a ptrace attach.
-		 */
-		if (!ret)
-			arch_ptrace_attach(child);
 		goto out_put_task_struct;
 	}
 
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 696c6490bd5b..bfa7452ca92e 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6353,10 +6353,7 @@ static void __sched notrace __schedule(unsigned int sched_mode)
 
 	/*
 	 * We must load prev->state once (task_struct::state is volatile), such
-	 * that:
-	 *
-	 *  - we form a control dependency vs deactivate_task() below.
-	 *  - ptrace_{,un}freeze_traced() can change ->state underneath us.
+	 * that we form a control dependency vs deactivate_task() below.
 	 */
 	prev_state = READ_ONCE(prev->__state);
 	if (!(sched_mode & SM_MASK_PREEMPT) && prev_state) {
diff --git a/kernel/signal.c b/kernel/signal.c
index e43bc2a692f5..edb1dc9b00dc 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -762,7 +762,10 @@ still_pending:
  */
 void signal_wake_up_state(struct task_struct *t, unsigned int state)
 {
+	lockdep_assert_held(&t->sighand->siglock);
+
 	set_tsk_thread_flag(t, TIF_SIGPENDING);
+
 	/*
 	 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
 	 * case. We don't check t->state here because there is a race with it
@@ -884,7 +887,7 @@ static int check_kill_permission(int sig, struct kernel_siginfo *info,
 static void ptrace_trap_notify(struct task_struct *t)
 {
 	WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
-	assert_spin_locked(&t->sighand->siglock);
+	lockdep_assert_held(&t->sighand->siglock);
 
 	task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
 	ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
@@ -930,9 +933,10 @@ static bool prepare_signal(int sig, struct task_struct *p, bool force)
 		for_each_thread(p, t) {
 			flush_sigqueue_mask(&flush, &t->pending);
 			task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
-			if (likely(!(t->ptrace & PT_SEIZED)))
+			if (likely(!(t->ptrace & PT_SEIZED))) {
+				t->jobctl &= ~JOBCTL_STOPPED;
 				wake_up_state(t, __TASK_STOPPED);
-			else
+			} else
 				ptrace_trap_notify(t);
 		}
 
@@ -1071,15 +1075,15 @@ static inline bool legacy_queue(struct sigpending *signals, int sig)
 	return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
 }
 
-static int __send_signal(int sig, struct kernel_siginfo *info, struct task_struct *t,
-			enum pid_type type, bool force)
+static int __send_signal_locked(int sig, struct kernel_siginfo *info,
+				struct task_struct *t, enum pid_type type, bool force)
 {
 	struct sigpending *pending;
 	struct sigqueue *q;
 	int override_rlimit;
 	int ret = 0, result;
 
-	assert_spin_locked(&t->sighand->siglock);
+	lockdep_assert_held(&t->sighand->siglock);
 
 	result = TRACE_SIGNAL_IGNORED;
 	if (!prepare_signal(sig, t, force))
@@ -1212,8 +1216,8 @@ static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
 	return ret;
 }
 
-static int send_signal(int sig, struct kernel_siginfo *info, struct task_struct *t,
-			enum pid_type type)
+int send_signal_locked(int sig, struct kernel_siginfo *info,
+		       struct task_struct *t, enum pid_type type)
 {
 	/* Should SIGKILL or SIGSTOP be received by a pid namespace init? */
 	bool force = false;
@@ -1245,7 +1249,7 @@ static int send_signal(int sig, struct kernel_siginfo *info, struct task_struct
 			force = true;
 		}
 	}
-	return __send_signal(sig, info, t, type, force);
+	return __send_signal_locked(sig, info, t, type, force);
 }
 
 static void print_fatal_signal(int signr)
@@ -1281,12 +1285,6 @@ static int __init setup_print_fatal_signals(char *str)
 
 __setup("print-fatal-signals=", setup_print_fatal_signals);
 
-int
-__group_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p)
-{
-	return send_signal(sig, info, p, PIDTYPE_TGID);
-}
-
 int do_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p,
 			enum pid_type type)
 {
@@ -1294,7 +1292,7 @@ int do_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p
 	int ret = -ESRCH;
 
 	if (lock_task_sighand(p, &flags)) {
-		ret = send_signal(sig, info, p, type);
+		ret = send_signal_locked(sig, info, p, type);
 		unlock_task_sighand(p, &flags);
 	}
 
@@ -1347,7 +1345,7 @@ force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t,
 	if (action->sa.sa_handler == SIG_DFL &&
 	    (!t->ptrace || (handler == HANDLER_EXIT)))
 		t->signal->flags &= ~SIGNAL_UNKILLABLE;
-	ret = send_signal(sig, info, t, PIDTYPE_PID);
+	ret = send_signal_locked(sig, info, t, PIDTYPE_PID);
 	spin_unlock_irqrestore(&t->sighand->siglock, flags);
 
 	return ret;
@@ -1567,7 +1565,7 @@ int kill_pid_usb_asyncio(int sig, int errno, sigval_t addr,
 
 	if (sig) {
 		if (lock_task_sighand(p, &flags)) {
-			ret = __send_signal(sig, &info, p, PIDTYPE_TGID, false);
+			ret = __send_signal_locked(sig, &info, p, PIDTYPE_TGID, false);
 			unlock_task_sighand(p, &flags);
 		} else
 			ret = -ESRCH;
@@ -2114,7 +2112,7 @@ bool do_notify_parent(struct task_struct *tsk, int sig)
 	 * parent's namespaces.
 	 */
 	if (valid_signal(sig) && sig)
-		__send_signal(sig, &info, tsk->parent, PIDTYPE_TGID, false);
+		__send_signal_locked(sig, &info, tsk->parent, PIDTYPE_TGID, false);
 	__wake_up_parent(tsk, tsk->parent);
 	spin_unlock_irqrestore(&psig->siglock, flags);
 
@@ -2184,7 +2182,7 @@ static void do_notify_parent_cldstop(struct task_struct *tsk,
 	spin_lock_irqsave(&sighand->siglock, flags);
 	if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
 	    !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
-		__group_send_sig_info(SIGCHLD, &info, parent);
+		send_signal_locked(SIGCHLD, &info, parent, PIDTYPE_TGID);
 	/*
 	 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
 	 */
@@ -2204,13 +2202,12 @@ static void do_notify_parent_cldstop(struct task_struct *tsk,
  * with.  If the code did not stop because the tracer is gone,
  * the stop signal remains unchanged unless clear_code.
  */
-static int ptrace_stop(int exit_code, int why, int clear_code,
-			unsigned long message, kernel_siginfo_t *info)
+static int ptrace_stop(int exit_code, int why, unsigned long message,
+		       kernel_siginfo_t *info)
 	__releases(&current->sighand->siglock)
 	__acquires(&current->sighand->siglock)
 {
 	bool gstop_done = false;
-	bool read_code = true;
 
 	if (arch_ptrace_stop_needed()) {
 		/*
@@ -2227,10 +2224,16 @@ static int ptrace_stop(int exit_code, int why, int clear_code,
 	}
 
 	/*
-	 * schedule() will not sleep if there is a pending signal that
-	 * can awaken the task.
+	 * After this point ptrace_signal_wake_up or signal_wake_up
+	 * will clear TASK_TRACED if ptrace_unlink happens or a fatal
+	 * signal comes in.  Handle previous ptrace_unlinks and fatal
+	 * signals here to prevent ptrace_stop sleeping in schedule.
 	 */
+	if (!current->ptrace || __fatal_signal_pending(current))
+		return exit_code;
+
 	set_special_state(TASK_TRACED);
+	current->jobctl |= JOBCTL_TRACED;
 
 	/*
 	 * We're committing to trapping.  TRACED should be visible before
@@ -2276,54 +2279,33 @@ static int ptrace_stop(int exit_code, int why, int clear_code,
 
 	spin_unlock_irq(&current->sighand->siglock);
 	read_lock(&tasklist_lock);
-	if (likely(current->ptrace)) {
-		/*
-		 * Notify parents of the stop.
-		 *
-		 * While ptraced, there are two parents - the ptracer and
-		 * the real_parent of the group_leader.  The ptracer should
-		 * know about every stop while the real parent is only
-		 * interested in the completion of group stop.  The states
-		 * for the two don't interact with each other.  Notify
-		 * separately unless they're gonna be duplicates.
-		 */
+	/*
+	 * Notify parents of the stop.
+	 *
+	 * While ptraced, there are two parents - the ptracer and
+	 * the real_parent of the group_leader.  The ptracer should
+	 * know about every stop while the real parent is only
+	 * interested in the completion of group stop.  The states
+	 * for the two don't interact with each other.  Notify
+	 * separately unless they're gonna be duplicates.
+	 */
+	if (current->ptrace)
 		do_notify_parent_cldstop(current, true, why);
-		if (gstop_done && ptrace_reparented(current))
-			do_notify_parent_cldstop(current, false, why);
+	if (gstop_done && (!current->ptrace || ptrace_reparented(current)))
+		do_notify_parent_cldstop(current, false, why);
 
-		/*
-		 * Don't want to allow preemption here, because
-		 * sys_ptrace() needs this task to be inactive.
-		 *
-		 * XXX: implement read_unlock_no_resched().
-		 */
-		preempt_disable();
-		read_unlock(&tasklist_lock);
-		cgroup_enter_frozen();
-		preempt_enable_no_resched();
-		freezable_schedule();
-		cgroup_leave_frozen(true);
-	} else {
-		/*
-		 * By the time we got the lock, our tracer went away.
-		 * Don't drop the lock yet, another tracer may come.
-		 *
-		 * If @gstop_done, the ptracer went away between group stop
-		 * completion and here.  During detach, it would have set
-		 * JOBCTL_STOP_PENDING on us and we'll re-enter
-		 * TASK_STOPPED in do_signal_stop() on return, so notifying
-		 * the real parent of the group stop completion is enough.
-		 */
-		if (gstop_done)
-			do_notify_parent_cldstop(current, false, why);
-
-		/* tasklist protects us from ptrace_freeze_traced() */
-		__set_current_state(TASK_RUNNING);
-		read_code = false;
-		if (clear_code)
-			exit_code = 0;
-		read_unlock(&tasklist_lock);
-	}
+	/*
+	 * Don't want to allow preemption here, because
+	 * sys_ptrace() needs this task to be inactive.
+	 *
+	 * XXX: implement read_unlock_no_resched().
+	 */
+	preempt_disable();
+	read_unlock(&tasklist_lock);
+	cgroup_enter_frozen();
+	preempt_enable_no_resched();
+	freezable_schedule();
+	cgroup_leave_frozen(true);
 
 	/*
 	 * We are back.  Now reacquire the siglock before touching
@@ -2331,14 +2313,13 @@ static int ptrace_stop(int exit_code, int why, int clear_code,
 	 * any signal-sending on another CPU that wants to examine it.
 	 */
 	spin_lock_irq(&current->sighand->siglock);
-	if (read_code)
-		exit_code = current->exit_code;
+	exit_code = current->exit_code;
 	current->last_siginfo = NULL;
 	current->ptrace_message = 0;
 	current->exit_code = 0;
 
 	/* LISTENING can be set only during STOP traps, clear it */
-	current->jobctl &= ~JOBCTL_LISTENING;
+	current->jobctl &= ~(JOBCTL_LISTENING | JOBCTL_PTRACE_FROZEN);
 
 	/*
 	 * Queued signals ignored us while we were stopped for tracing.
@@ -2360,7 +2341,7 @@ static int ptrace_do_notify(int signr, int exit_code, int why, unsigned long mes
 	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
 
 	/* Let the debugger run.  */
-	return ptrace_stop(exit_code, why, 1, message, &info);
+	return ptrace_stop(exit_code, why, message, &info);
 }
 
 int ptrace_notify(int exit_code, unsigned long message)
@@ -2471,6 +2452,7 @@ static bool do_signal_stop(int signr)
 		if (task_participate_group_stop(current))
 			notify = CLD_STOPPED;
 
+		current->jobctl |= JOBCTL_STOPPED;
 		set_special_state(TASK_STOPPED);
 		spin_unlock_irq(&current->sighand->siglock);
 
@@ -2532,7 +2514,7 @@ static void do_jobctl_trap(void)
 				 CLD_STOPPED, 0);
 	} else {
 		WARN_ON_ONCE(!signr);
-		ptrace_stop(signr, CLD_STOPPED, 0, 0, NULL);
+		ptrace_stop(signr, CLD_STOPPED, 0, NULL);
 	}
 }
 
@@ -2585,7 +2567,7 @@ static int ptrace_signal(int signr, kernel_siginfo_t *info, enum pid_type type)
 	 * comment in dequeue_signal().
 	 */
 	current->jobctl |= JOBCTL_STOP_DEQUEUED;
-	signr = ptrace_stop(signr, CLD_TRAPPED, 0, 0, info);
+	signr = ptrace_stop(signr, CLD_TRAPPED, 0, info);
 
 	/* We're back.  Did the debugger cancel the sig?  */
 	if (signr == 0)
@@ -2612,7 +2594,7 @@ static int ptrace_signal(int signr, kernel_siginfo_t *info, enum pid_type type)
 	/* If the (new) signal is now blocked, requeue it.  */
 	if (sigismember(&current->blocked, signr) ||
 	    fatal_signal_pending(current)) {
-		send_signal(signr, info, current, type);
+		send_signal_locked(signr, info, current, type);
 		signr = 0;
 	}
 
@@ -4807,7 +4789,7 @@ void kdb_send_sig(struct task_struct *t, int sig)
 			   "the deadlock.\n");
 		return;
 	}
-	ret = send_signal(sig, SEND_SIG_PRIV, t, PIDTYPE_PID);
+	ret = send_signal_locked(sig, SEND_SIG_PRIV, t, PIDTYPE_PID);
 	spin_unlock(&t->sighand->siglock);
 	if (ret)
 		kdb_printf("Fail to deliver Signal %d to process %d.\n",
diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
index 0a97193984db..cb925e8ef9a8 100644
--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -870,7 +870,7 @@ static inline void check_dl_overrun(struct task_struct *tsk)
 {
 	if (tsk->dl.dl_overrun) {
 		tsk->dl.dl_overrun = 0;
-		__group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
+		send_signal_locked(SIGXCPU, SEND_SIG_PRIV, tsk, PIDTYPE_TGID);
 	}
 }
 
@@ -884,7 +884,7 @@ static bool check_rlimit(u64 time, u64 limit, int signo, bool rt, bool hard)
 			rt ? "RT" : "CPU", hard ? "hard" : "soft",
 			current->comm, task_pid_nr(current));
 	}
-	__group_send_sig_info(signo, SEND_SIG_PRIV, current);
+	send_signal_locked(signo, SEND_SIG_PRIV, current, PIDTYPE_TGID);
 	return true;
 }
 
@@ -958,7 +958,7 @@ static void check_cpu_itimer(struct task_struct *tsk, struct cpu_itimer *it,
 		trace_itimer_expire(signo == SIGPROF ?
 				    ITIMER_PROF : ITIMER_VIRTUAL,
 				    task_tgid(tsk), cur_time);
-		__group_send_sig_info(signo, SEND_SIG_PRIV, tsk);
+		send_signal_locked(signo, SEND_SIG_PRIV, tsk, PIDTYPE_TGID);
 	}
 
 	if (it->expires && it->expires < *expires)